Process optimization of peroxide injection during polyethylene production

Abstract

In a process for the high-pressure polymerization of ethylene in a high-pressure autoclave or in a high-pressure tube reactor having one or more metering points for one or more peroxides, no peroxide or a reduced amount of peroxide is metered in during the time interval in which the pressure is lowered by opening a pressure maintenance valve and the original amount of peroxide per unit time is metered in again as soon as the pressure after closure of the pressure maintenance valve has built up again so that it exceeds 90% of the pressure difference between nominal pressure and lowered pressure.

We claim:  
     
       1. A process for the high-pressure polymerization of ethylene in a high-pressure autoclave or in a high-pressure tube reactor having one or more metering points for one or more peroxides, wherein no peroxide or a reduced amount of peroxide is metered in during the time interval in which the pressure is lowered by opening a pressure maintenance valve and the original amount of peroxide per unit time is metered in again as soon as the pressure after closure of the pressure maintenance valve has built up again so that it exceeds 90% of the pressure difference between nominal pressure and lowered pressure. 
     
     
       2. A process as claimed in  claim 1 , wherein the amount of peroxide metered in during the pressure-reduction procedure is reduced by at least 15% of the original amount. 
     
     
       3. A process as claimed in  claim 1 , wherein the amount of peroxide metered in during the pressure-reduction procedure is reduced by from 15 to 90% of the original amount. 
     
     
       4. A process as claimed in  claim 1 , wherein the amount of peroxide metered in during the pressure-reduction procedure is reduced by from 30 to 40% of the original amount. 
     
     
       5. A process as claimed in  claim 1 , wherein the amount of peroxide metered in during the pressure-reduction procedure is reduced by from 45 to 55% of the original amount. 
     
     
       6. A process as claimed in  claim 1 , wherein the amount of peroxide metered in during the pressure-reduction procedure is reduced by from 60 to 70% of the original amount. 
     
     
       7. A process as claimed in  claim 1 , wherein the amount of peroxide metered in during the pressure-reduction procedure is reduced by from 70 to 80% of the original amount.